Debug a failed file upload/conversion (.pptx)

[a.og...@entouch.co.jp]

I receive this error when converting this particular .pptx (other .pptx docs convert fine)

REDIS: {"header":{"name":"PresentationConversionUpdateEvtMsg","meetingId":"1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889","userId":"notUsedYet"},"body":{"messageKey":"OFFICE_DOC_CONVERSION_INVALID","code":"OFFICE_DOC_CONVERSION_INVALID","presentationId":"09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865","presName":"test.pptx"}} emitted

  size is 1.5 mb, 2 slides.

I also checked bbb-web.log

org.bigbluebutton.presentation.SupportedDocumentFilter  - Received supported file /var/bigbluebutton/1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889/1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889/09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865/09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865.pptx

2019-01-21T16:33:03.867+09:00 INFO  org.bigbluebutton.presentation.imp.OfficeDocumentValidator2  - Running pres check timeout 20 /usr/share/prescheck/prescheck.sh /var/bigbluebutton/1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889/1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889/09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865/09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865.pptx

2019-01-21T16:33:06.114+09:00 ERROR org.bigbluebutton.presentation.imp.OfficeDocumentValidator2  - -- analytics -- {"filename":"test.pptx","meetingId":"1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889","message":"PPTX failed validation.","presId":"09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865"}

2019-01-21T16:33:06.114+09:00 WARN  org.bigbluebutton.presentation.imp.OfficeToPdfConversionService  - -- analytics -- {"filename":"test.pptx","meetingId":"1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889","message":"Problems detected prior to converting the file to PDF.","presId":"09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865"}

2019-01-21T16:33:06.114+09:00 INFO  org.bigbluebutton.presentation.OfficeToPdfConversionSuccessFilter  - Notifying of OFFICE_DOC_CONVERSION_INVALID for /var/bigbluebutton/1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889/1b47c042070759f89a0538c015e1003a06cf62f9-1548055374889/09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865/09a7c92f46314cc5e8cabebc2878bd36a09d1100-1548055978865.pptx

How can I debug more into PPTX failed validation.?

Are there any other logs I can check might help debugging? File opens fine in LibreOffice 6.1 and MS Office, I can even export to .pdf


Thanks,
Ally.

[a.og...@entouch.co.jp]

forgot this:

BigBlueButton Server 2.0.0-RC9 (1176)

                    Kernel version: 4.15.0-1014-gcp

                      Distribution: Ubuntu 16.04.5 LTS (64-bit)

and 4 of these:

libreoffice --version

LibreOffice 5.1.6.2 10m0(Build:2)

[Anatoliy Vinogradov]

Hi, Ally. As I know, the ppt and pptx format often behaves strangely when loaded. This problem occurs in many webinar services. Starting to create a file name, ending with fonts, pictures, indents from the edge of the slide when creating slides. This problem is solved by converting the document to pdf. In pdf format, documents in 99% of cases are converted and displayed perfectly.

понедельник, 21 января 2019 г., 10:05:55 UTC+2 пользователь a.og...@entouch.co.jp написал:

[a.og...@entouch.co.jp]

In this case however the pre-check code failing is from BBB? Maybe the team can shed some light.

cat /usr/share/prescheck/prescheck.sh

java -cp "/usr/share/prescheck/lib/*" org.bigbluebutton.prescheck.Main $@

My therapist says I am not allowed to look at Java code anymore, so if anyone can shed some light, I (and my therapist) would be very happy.

 

[Chad Pilkey]

I think the presentation will be failing one of these three checks, https://github.com/bigbluebutton/bigbluebutton/blob/v2.0.x-release/bigbluebutton-web/pres-checker/src/main/java/org/bigbluebutton/prescheck/Main.java#L39-L41. Unfortunately there's no logging to tell which one of them is the culprit. The first check is for .emf elements. This issue has an explanation https://github.com/bigbluebutton/bigbluebutton/issues/6585. The second check is for complicated backgrounds (the ones with lots of tiny squares). The third check is for an empty presentation.

[a.og...@entouch.co.jp]

Thanks for the code links. So, against my every desire not to look at Java ;) ... I put a println on

https://github.com/bigbluebutton/bigbluebutton/blob/v2.0.x-release/bigbluebutton-web/pres-checker/src/main/java/org/bigbluebutton/prescheck/Main.java#L95

I see all the image types (29 images in the pptx) one of which is "image/x-emf". So after googling "what is image/x-emf!?", I seem to understand it is an "EnhancedMetaFile" format - some kind of MS Office meta data rubbish for printers (?!).

My followup Q's are;

- Is this really a blocker for converting a file? (Sorry for my ignorance, but I just learnt about x-emf!)

- If we can get this level of debug detail, could it be reflected in a) server log or, even better b) the conversion GUI (with suggested troubleshooting solutions).

I was able to remove the meta rubbish by opening the document in LibreOffice and re-saving it. It's not a work-around that I am happy with at the moment, if BBB could automate this that would be fantastic.

[Chad Pilkey]

I think the idea is that the EMF image wouldn't be rendered in the final result and if someone was making extensive use of them then there will be a big variance between what is shown and what is expected. The language around the error could also definitely be improved in both the logs and what is presented to the user. The presentation validation and checking has grown over time as we discover problem presentations and the feedback hasn't been kept up to match that. I opened an issue on Github for adding new log messages, https://github.com/bigbluebutton/bigbluebutton/issues/6611. The improvement for the logs wouldn't be too hard to add, but the priority would probably be low.

[Fred Dixon]

Hi Ally,

It's definitely the embedded EMF that is causing the PPTX to not convert.  However, if they save it first as a PDF and then upload it, BigBlueButton should display the PDF without issue.

Regards,... Fred

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[a.og...@entouch.co.jp]

Supporting only PDFs is not an ideal user experience, and some-what of a deal breaker for us to use BigBlueButton :/

If you tell any customer in our business region; "we cannot guarantee a file conversion with non-PDF files" you will get this response:

"Is it perhaps misleading to support non-PDF file types if it is not guaranteed to be supported?". 

Our customers care that an enabled feature of a quality working product must satisfy 100% of the time. I do not know how common embedded EMF is for MS Office users, but given that we hit this issue relatively quickly after using BBB, I think we could make safe assumptions that it could be quite common.

Should we restrict file uploads to PDF only? Is this configurable?

Thanks.

[Fred Dixon]

Hi Ally,

Thanks for the feedback!

> "Is it perhaps misleading to support non-PDF file types if it is not guaranteed to be supported?". 

BigBlueButton uses Liberoffice to convert PPT/PPTX to PDF documents and, for most documents, it works remarkably well.  

There are some documents that trigger a subtle subtle conversion that most never notice.  If a particular slide had many large images, that slide will first get converted to an image itself and then the image will get converted to it's final form of a SWF file (Flash) or SVG (HTML5).  Slides that have embedded audio and video also get "flattened" as Libreoffice is converting the slides to PDF internally before the final form.  Any transitions and animations get flattened too.

And then there are documents that Libreoffice can't convert -- specifically those that include include Enhanced Metafile ("EMF") content..  EMF is also used as a graphics language for printer drivers.  We don't have any stats, but we've seen very few documents over the years that have EMF content.  You'll see it when embedding an Illustrator graphic in the PPTX, for example

  https://heatherackmann.com/convert-an-illustrator-vector-graphic-to-a-powerpoint-shape

Given PowerPoint has pretty good built-in drawing tools, most presentations don't have EMF embedded.  But, for those that do, we can do a better job of communicating to the user what is the issue.

  https://github.com/bigbluebutton/bigbluebutton/issues/6611

Regards,... Fred

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